This invention relates generally to a method for classification of atrial arrhythmias. More particularly, it relates to a system for developing a database of body surface ECG flutter wave maps for the classification of the type and rotation of atrial flutter.
Clinical electrocardiography of counterclockwise (CCW) typical atrial flutter (also known as common or type I atrial flutter) dates back to the early part of the 20th century. The continuous or xe2x80x9csawtoothxe2x80x9d pattern of the flutter wave in standard ECG leads II and III was first reported and attributed to an atrial impulse circulating around both caval veins. Later reports provided further evidence to the concept of an excitation wave rotating in a CCW direction in the right atrium and giving rise to the distinct xe2x80x9csawtoothxe2x80x9d pattern with predominantly negative flutter waves in the inferior leads and V6 combined with a positive flutter wave in V1. With the introduction of multisite endocardial mapping, entrainment techniques, and catheter ablative strategies in the therapeutic management of the typical form of atrial flutter, flutter wave propagation has been convincingly demonstrated to occur in a macroreentrant right atrial circuit confined anteriorly by the tricuspid annulus and posteriorly by the crista terminalis and its inferior extension the eustachian ridge, which act as natural barriers to conduction. In addition to CCW rotation of the flutter wave, it has been shown that clockwise (CW) impulse rotation in the same right atrial circuit can be frequently observed. Although there is general consensus on the previously mentioned distinct morphology of the standard 12-lead electrocardiogram (ECG) during CCW typical atrial flutter, ECG features found to be most specific for CW typical atrial flutter are more variable. Visual assessment of the flutter wave polarity on the standard 12-lead ECG is hampered by low voltage, a continuously undulating signal, and QRST wave obscurement when a low degree of atrioventricular (AV) block is present. Moreover, the standard 12-lead ECG has been found insufficient in distinguishing between CCW and CW typical atrial flutter or between the two forms of typical and atypical atrial flutter.
Consequently, electrocardiographic determination of the type (typical or atypical) and rotation (CCW or CW for typical) of atrial flutter is often hampered by inaccurate and inconclusive scalar waveform analysis of the standard 12-lead ECG. This may then require more invasive techniques being employed to obtain further information or a misdiagnosis may occur, both of which increase patient risk and expense. Such additional information may be needed to select an appropriate therapy, e.g., radiofrequency catheter ablation, or anti-arrhythmic drugs.
There is a need, therefore, for an improved ability to discriminate the type and rotation of atrial flutter.
Accordingly, it is a primary object of the present invention to provide a system for developing a database of body surface ECG flutter wave data maps. It is a further object of the invention to provide an apparatus for classifying typical and atypical atrial flutter for said database. It is an additional object of the invention to provide a method of storing a database of mean body surface ECG flutter wave data map patterns in a computer-readable medium for retrieval, analysis and sharing. The database will then contain data maps for comparison to patient body surface ECG flutter wave data maps to improve detection and classification of atrial flutter.
The aforementioned objects and advantages are attained by developing a database of body surface ECG flutter wave data maps for classification of typical or atypical atrial flutter. The present invention also includes a method and apparatus for generating the database. The method generally comprises generating atrial flutter data in a subject; receiving the atrial flutter data from the subject; classifying the data as typical clockwise (CW) or counterclockwise (CCW) and atypical atrial flutter; averaging the classified data obtained from one or more subjects; and storing and accessing the averaged data in the database. The flutter wave data may be in the form of data maps such as flutter wave potential maps or flutter wave integral maps. The maps are classified as being characteristic body surface maps specific to CCW or CW typical or atypical atrial flutter data. The atrial flutter may be induced in the subject by electrically stimulating the arrhythmogenic substrate of the atrium using a probe. The data may be verified before averaging. The mean maps may then be calculated from verified atrial flutter wave maps to construct a database of characteristic body surface ECG flutter wave maps.
The mean flutter wave maps in the database can be used to automatically characterize flutter wave data from a patient as being typical CW, typical CCW or atypical atrial flutter.